In order to be able to detect cases where DMA isn't capable of
reaching every memory address, port the concept of DMA mask,
dma_set_mask() function and add appropriate check to
dma_mapping_error().

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>